From your biased, subjective point of view that has nothing to do with the objective facts of language, maybe.

verbing a word that isn't commonly verbed? that's the main thing i love in the English langauge, the flexibility to fuck around with it and still be understood by others without having to explain what you're doing

Using the suffix -er for a two syllable word isn't any correcter than verbing a noun and would probably make quite a few English teachers red in the face.

Both have a linguistic use; the verb "vaguing" is a shortened form of the cumbersome "vague-posting", while "stupider" is a more emphatic and/of colloquial form of "more stupid". Neither can be replaced by their more formal form without changing the meaning of the sentence slightly.

Objectively they are very similar linguistic quirks, the only reason you'd use one but dislike the other is familiarity. Why dismiss it out of hand when you can excitedly marvel at a novel way people can remotely transfer thoughts?

i mean, you understood the meaning of the sentence, right? so the person managed to get their point accross, and saved on length by using that form - that's actually quite linguistically clever!

Nope, I can do this all day. Other fun examples of backformation off the top of my head are: "to burgle" from "burglar" (which the Brits still get mad about (note: this is incorrect, see conversation below)), originally from the Latin agent noun burglator from the verb burgare; and "cherry", backformed from Old French cerise, which was reinterpreted as a plural (even though it wasn't one), and then a new singular form was backformed. The same thing happened to "pea" (though that's a native English word) - you can still see the original "pease" in the old nursery rhyme: "Pease porridge hot, pease porridge cold, pease porridge in a pot nine days old".